CBN grinding wheels

[Sonic EscapeParticipant @sonicescape38234]

Anybody has any experience with CBN wheels for HSS tools? It seems to me that they have only advantages comparing with aluminium oxide types. No dust, no danger of breaking apart, no need to dress it, no glazing and perfectly balanced out of the box. I think I’ll buy one for my bench grinder. Just can’t figure out what grit size to use, maybe 180?

[John HaineParticipant @johnhaine32865]

Seems to be a very limited choice anyway, only seen 80 and 180 grit.  I have the latter, excellent.  80 would be too coarse I think.

[VicParticipant @vic]

They are quite popular with some Woodturners.

[Sonic Escape]

On 23 May 2024 at 14:25 Sonic Escape Said:

… seems to me that they have only advantages comparing with aluminium oxide types…

Apart from the price, 2 to 5 times more than an aluminium wheel!

In my workshop, CBN is unlikely to be ‘value for money’ because it takes me so long to wear out a grinding wheel.

I also use the same wheel ‘general-purpose’ on mild-steel and non-ferrous metals.  I understand CBN to excel at grinding hardened steel, but is it good for anything else?

Dave

[Sonic EscapeParticipant @sonicescape38234]

Yes, the longer life of CBN is of little value for hobby users. But the lack of dust is a serious improvement. Before finding out about CBN I was considering mounting the bench grinder on a small frame with wheels. To take it outside when grinding.

[DiogenesParticipant @diogenes]

I have a bench made from a heavy wooden crate made for exactly that purpose.

It has two wheels on the front so I can wheel it about (outside!) and two feet on the back so it remains stationary and stable when I park it.

I need to make a steel top.

Grinding and welding are both jobs that are better in the great outdoors.

Is CBN any good for cleaning up the edges / ends of rusty old steel?

[SillyOldDuffer]

On SillyOldDuffer Said

I also use the same wheel ‘general-purpose’ on mild-steel and non-ferrous metals.

Are you sure it’s safe to grind non-ferrous on a GP wheel?    Where I used to work it was a serious disciplinary offence to use the workshop off-hand grinder for non-ferrous.

I recall it happening once – the wheels were immediately changed, and as the person responsible wasn’t identified the isolator for the grinder was padlocked from then on, with key having to be signed out only by trained personnel.

 

[bernard towersParticipant @bernardtowers37738]

I have a cbn cup wheel on my t & c grinder and as you say no dust just grinding debris, I use it for drills up to about 1/4 inch

[bernard towers]

On bernard towers Said:

I have a cbn cup wheel on my t & c grinder and as you say no dust just grinding debris, I use it for drills up to about 1/4 inch

Where did you buy it? I’ve only seen Diamond cup wheels so far.

[David Jupp]

On David Jupp Said:

On SillyOldDuffer Said

I also use the same wheel ‘general-purpose’ on mild-steel and non-ferrous metals.

Are you sure it’s safe to grind non-ferrous on a GP wheel?    Where I used to work it was a serious disciplinary offence to use the workshop off-hand grinder for non-ferrous.

…

 

¡Ay, caramba!  Now the question has been asked, I am absolutely not sure it’s safe to grind non-ferrous on a GP wheel!  I assume it is, as in ‘ass of u and me’.

Although I have a good library and an engineering background, most of my workshop skills are self-taught.   The learning is a big part of the fun and interest, but the teacher (me) isn’t trustworthy.   Although the gaps in my education show up as spoilt work and agonisingly slow progress rather than blood-spattered misadventures,  I could well be wrong on this one!

Is the objection to grinding non-ferrous that a damaged wheel could disintegrate, or that it tends to choke the grit, requiring redressing before it can be used on steel?

Although I’ve never had any trouble grinding non-ferrous metals,  that’s not good evidence.  The accident rate on a misused grinding wheel might be something like 1 burst per 500 hours of operation.  As a SillyOldDuffer pootling around his shed might take decades to put a 1000 hours on his grinder, it’s easy for him to be convinced what he’s doing is completely safe, when actually it’s somewhat risky.  Personal experience on it’s own ain’t good enough.  The bad consequence of misusing a wheel will probably only appear when a grinder is kept busy, for example one that sharpens tools for several machinists could run up a 500 hours hard work in a year.    It’s the accident statistics that reveal the truth, the sum of many reports, not individual opinions.

How bad the accident is when it occurs is also variable.  Anything between wheels that fall apart harmlessly to a burst violent enough to blind the chap who doesn’t believe in safety glasses because he’s never been blinded before!

What do others think?  In the meantime I shall stop grinding non-ferrous on the wheel.  My small sanding machine used as a linisher  should be a safe alternative, albeit slower.

Dave

[Sonic EscapeParticipant @sonicescape38234]

I also have a cup wheel but I always thought it is a diamond wheel. Could it be CBN? The grit is W28, equivalent of 500-600 I think.

 

 

[John HaineParticipant @johnhaine32865]

That looks like diamond to me.  CBN has the grit embedded in metal surface

[SillyOldDuffer]

On SillyOldDuffer Said:

 

I also use the same wheel ‘general-purpose’ on mild-steel and non-ferrous metals.

Dave

I was always taught never to grind Ali on a grinding wheel where steel also is being ground on the same wheel and if caught a severe reprimand soon followed.

 

All the woodturners that I know that own a CBN highly recommend them, Please also note that woodturners also tend to touch up (Grind) their tools a lot more than metalworkers do as wood can be very abrasive and soon take the edge off of woodturning tools.

Just turning a simple bowl, a trip to the grinder can be anywhere up to10 times and occasionally more if very hard or in some cases where silica is present in the wood

[bernard towersParticipant @bernardtowers37738]

My CBN wheel is made the same way as the one pictured and its an English manufactured one

[Sonic EscapeParticipant @sonicescape38234]

I can’t remember where but I read that when you mix soft metals with steel on the same wheel you can embed steel particles in the softer material. There was also a picture with rust spots on an aluminum part.

And here is what Machining Fundamentals recomends:

 

[bernard towers]

On bernard towers Said:

My CBN wheel is made the same way as the one pictured and its an English manufactured one

And is has the same color? I want to figure out what kind of wheel I have. I read that carbide tools destroy the CBN wheels.

While I was browsing the Machining Fundamentals looking for the page from above I found some info about electrolytic grinding. I looks like an alternative to CBN to get rid of the dust. Looking at the cables I guess some serious current is required. I think it has even cable drop compensation connection!

 

 

[VicParticipant @vic]

Although the target audience is woodworkers, this Video is quite interesting.

IF YOU CANT SEE THE VIDEO KEEP RELOADING THIS PAGE UNTIL IT APPEARS.

[John Haine]

On John Haine Said:

That looks like diamond to me.  CBN has the grit embedded in metal surface

Well, that’s not always the case.

Here is a picture of my CBN wheel (coming from somewhere in the very far East iirc) on my Thommen grinder

 

And another picture of 3 different Diamond wheels. The left pair comes from ARC, the one to the right from Eternal tools.

Sorry, can’t move the text above the picture… Same problem as in the old forum.

Regards, Hans

[VicParticipant @vic]

If you do a search for CBN Cup wheel you get hits like this.

But you also get this. Is it CBN or Diamond?

 

[Sonic Escape]

On Sonic Escape Said:

I also have a cup wheel but I always thought it is a diamond wheel. Could it be CBN? …

 

Always a problem buying second-hand tools;  what the h*ll is it, and is it in reasonable condition?

Unless the wheel can be identified by a part number, the only way to find out is to try it. CBN lasts a lot longer on steel than diamond, and the latter might spoil a critical job.

Maybe a hybrid mix of CBN and diamond, or something ordinary.

Dave

 

 

[VicParticipant @vic]

I wonder if this plated wheel is Diamond or CBN? They seem quite popular for some of the tool grinders I’ve seen.

 

[Michael GilliganParticipant @michaelgilligan61133]

This may be of interest … they appear to know their stuff:

https://ukam.com/diamond-vs-cbn-cubic-boron-nitride-tools/#:~:text=similar%20to%20diamond.-,CBN%20is%20the%20second%20hardest%20material%20known%20after%20diamond%20and,%2C%20cast%20iron%2C%20and%20superalloys.

MichaelG.

 

[mark costello 1Participant @markcostello1]

I sometimes grind aluminum or soft materials on an aluminum oxide wheel. It is not usually much, not left gobbed on. Afterwards the wheel is dressed and the aluminum disappears. No problems.

[noel shelleyParticipant @noelshelley55608]

The real problem with mixed metals on a grinder is alli and the THERMIT reaction ! That’s  when accidents get REALLY nasty ! Look it up ! YES it does happen and many moons ago it was mentioned in ME. Noel.

[Author]

Posts